The objective of this study was to introduce a new battery for cognitive assessment in Egyptian elderly and to present the rationale behind its construction. This new neuropsychological battery was designed to overcome defects in existing dementia screening instruments and their inability to detect early cognitive impairment by assessments of verbal learning, short- and long-term memory, cued memory, short-term and working memory, visuospatial functions, executive functions, verbal fluency, and confrontation naming, assessing the effect of depression on those tests and to apply tests that are less affected by education.
MMSE is one of the most widely used tests for cognitive screening all over the world and though conflicts exist regarding its accuracy, the American Academy of Neurology in its guidance and the Alzheimer’s Association in their guidance suggested MMSE as an important tool for cognitive screening [41], so it was used in this study as a standard test using the cut off points ≤ 22 for participants > 9 years education and ≤ 21 for illiterate participants and those with < 9 years education [30].
For the validity and reliability of the new battery, test re-test reliability of each battery subset was done. Significance between battery tests and DSMIV dementia was calculated, then the sample was divided into two groups; participants who are illiterates till ≤ 9 years education and another one with participants > 9 years education. Each group was divided into normal, mild cognitive impairment (MCI), and dementia according to MMSE scores.
MMSE was divided into three quadrants to measure normal, MCI, and dementia and to compare battery tests to it and mean and standard deviation for each battery subset in each group was determined. Then F value and post HOC were calculated to measure significance and to confirm where the differences occurred between groups using criterion group validity.
Following the measures taken by Morrison and colleges in 2015 [42] to test reliability, 20 participants were included in the pre-post sample to test reliability of the current study. The 20 participants took the battery and were invited to take the battery 28 days after the first administration by the same clinician. Test-retest reliability of the current battery was calculated with Pearson correlations and 95% CIs and Spearman’s rho for each subtest.
The analytic test-retest reliabilities of the current battery scores ranged from adequate to high (i.e., r = .7 and higher) in most of the battery subsets. The values of some tests (distractor interval easy, visuospatial copy and recall, digit span length, spherical and letter fluencies) were lower (r < 0.7). These results match the validation results of Calamia and colleges in 2013 [43] which revealed reliability in most of their results except for some memory and executive functioning scores which in both studies could be contributed to practice effects.
Calamia and collegues in 2012 [44] reported in their meta-analysis that practice effects tend to be more evident on certain tests (e.g., memory, processing speed, which can affect recall, spherical, and letter fluencies respectively) than others (e.g., visuospatial abilities, verbal knowledge), with considerable variability within different cognitive domains and some variation with different methods of assessment. They also reported that age, retest interval whether long or short could influence the amount and direction of practice effects.
For validation purpose of the current study, significance between battery tests in normal and dementia patients diagnosed according to and DSM-IV criteria for dementia were measured; results showed significant difference in most of the battery tests; verbal learning, distractor interval, delayed recall, word recognition, figure copying and recall, modified trails, confrontation naming, and abstraction. However, there was no significance between normal and dementia patients regarding digit span, stimulus cueing of confrontation naming, and judgment (judgment almost reached a statistical significance).
Upon classifying the battery tests according to three quadrants of MMSE into normal, MCI, and dementia, among the group with > 9 years education, most battery tests showed highly significant difference between 3 subgroups (e.g., verbal learning, word recognition, figure copy and recall, delayed recall, distractor interval, set shifting time, confrontation naming, digit span backward, lexical and semantic fluency) with less extent of significance for digit span forward, phonemic cueing of confrontation naming, and abstraction.
In illiterate and low-educated people, there was statistically significant difference between the 3 groups regarding semantic fluency, verbal learning, figure copy and recall, distractor interval, set shifting time, and confrontation naming. However, digit span forward and backward, phonemic cuing of confrontation naming, abstraction, and judgment showed no difference.
Overall, the battery showed good ability to differentiate between normal, MCI, and dementia people and the study showed that the battery is valid and reliable to diagnose MCI and dementia.
Regarding education, the current study showed no statistically significant association between levels of education and the following tests; verbal learning, distractor interval, delayed recall, word recognition, visuospatial figure copying and recall, set shifting abilities, forward digit span, animals and spherical fluencies, confrontation naming, stimulus and phonemic cuing, abstraction, and judgment. This denotes the ability of the battery to be applied on illiterate subjects. However, there was highly statistically significant difference regarding backward digit span and letter fluency.
These results are concordant with Kwon et al.’s [45] results which showed insignificance in forward digit span, verbal word recognition, and animals’ fluency regarding education. However, their study stated that the performance of the illiterate subjects was worse than that of literate subjects in visuospatial functions and verbal learning test.
The difference between their study and the current study in visuospatial functions could be attributed to the more complexity of Rey-Osterrrieth figure used in their study in comparison to the simple Bender copy in the current study and to the more time delay (20 min) in comparison to 10 min in the current study. Kwon et al. 2015 [45] applied the Seoul Verbal Learning Test (SVLT) which is formed of three learning-free recall trials of 12 words which is more difficult than the paired associate of Wechsler applied in the current study which compresses three learning associate recall trials of 10 words.
A study done in Turkey by Akdag and colleagues in 2013 [46] using Hodkinson Abbreviated Mental Test (which assessed working, short and long-term memory, attention, orientation, and general fund of information) to screen for dementia in elderly people also found no effect of education on cognitive function.
The new battery of current study will be under the name of Ain Shams Cognitive Assessment (ASCA) scale.